1. Field of the Application
The present application relates to a gas valve with an auxiliary shutter inside a main shutter. The present application also concerns an electrovalve with a solenoid, the plunger of which is immersed in the fluid.
2. Description of Related Art
In order to control the distribution of a fluid, the distribution circuits are equipped with electrovalves. An electrovalve is generally fitted with an actuator, for example a solenoid which drives a shutter of a valve between a closed position and an open position. As a safety measure, the electrovalve may be configured such that the pressure of the fluid holds it closed. In this case, the pressure exerts a closing force against the shutter which is proportional to said pressure. In response, the electrovalve must be dimensioned so as to counterbalance the closing force.
In the context of a high-pressure application, the solenoid must be massive and heavy in order to provide a sufficient opening force. This effect on the mass then becomes critical on installation in an aircraft. There is therefore a need to reduce the closing force. A known solution consists of splitting the shutter into a main shutter and an auxiliary shutter which opens and closes an orifice in the main shutter. This orifice is configured so as to create a pressure balance on either side of the main shutter in order to facilitate its actuation. The opening force is reduced since the pressure difference applies only to the auxiliary shutter, and hence essentially the dimensions are reduced.
Document U.S. Pat. No. 4,928,733 A discloses a valve with a main body, a main shutter and an auxiliary shutter. The main shutter comprises a lower bore which the auxiliary shutter may close. The latter is also able to drive the main shutter in the opening and closing directions. Closure and drive during closure are carried out by means of an auxiliary shutter head. The valve comprises a guide to accompany the main shutter, in addition to the auxiliary shutter rod on which it slides. On opening of the auxiliary shutter, a leakage flow takes place between the main shutter and its guide. Then the pressure balance around the auxiliary shutter is achieved using axial channels produced in the mass of the main shutter.
This valve allows a reduction in the opening force. Its architecture however is difficult to produce. It has complex shapes and a portion arranged in a cavity with poor access. Also the opening is not progressive. In the context of an application for high-pressure gas, the opening movement of the auxiliary shutter generates a pressure peak which can damage associated equipment.
Although great strides have been made in the area of gas valves, many shortcomings remain.